As long as the field of package design has existed, the consensus has been that a product’s package serves two basic functions: communicate with the consumer, and provide passive protection of the product inside. But new developments in polymer chemistry could be adding a new possibility in just a few years’ time. Researchers are calling this concept “active packaging”, and it’s pretty darn cool. Read more…
What does active packaging mean?
Think about any traditional food package: a bag of potato chips, a can of tomato sauce, a vacuum-sealed package of lunch meat. Just like a seatbelt in a car, all of these packages passively protect the food products inside. Active packaging would be more like your anti-lock brakes. This packaging would be actively doing something to protect the product.
The concept was developed by researchers at Penn State University’s College of Agricultural Sciences. They have been experimenting with a type of film that can be used on packaged meat and poultry products that not only passively protects the contents from external agents, but actively supplies antimicrobial compounds to the meat to keep it safer and fresher.
And lest you go worrying that this is just another example of food companies injecting antibiotics into the process at any possible juncture, there are no antibiotics involved in this new active packaging concept at all. Instead, the researchers experimented with two different essential oils and two different types of nanoparticles – all completely natural and food-safe compounds. Oregano essential oil, rosemary essential oil, zinc oxide nanoparticles and silver nanoparticles were all found to inhibit bacterial growth on packaged meats.
Antimicrobial packaging materials
To develop a type of plastic wrap in which these natural antimicrobials could be incorporated, researchers turned to the polymer film known as pullulan. The film is named for the organism that produces it, the fungus Aureobasidium pullulans. The fungus digests sugar syrup and forms a polysaccharide film that is edible, odorless and practically tasteless. Pullulan film is already used in the food and health industry to make oral dissolving strips (like Listerine PocketPaks) and as an alternative to gelatin in making candies, capsules and tablets.
The natural polymer has several properties which make it a good fit for packaging applications, including heat sealability and low permeability to oxygen. And of course, it allows different compounds to be incorporated into the film’s molecular structure, whether it be mouthwash or nanoparticles.
However, there are some challenges facing this active packaging. For one, pullulan is water soluble (which is why those strips dissolve on your tongue), so it wouldn’t necessarily provide adequate protection as a packaging material on its own. It also has higher permeability to oxygen than the polyethylene films currently favored by the meat packaging industry. Polyethylene, of course, doesn’t allow these sorts of antimicrobial compounds to be incorporated within it.
Researchers at Penn State are now trying to figure out a way to combine these two materials into one simple packaging step. From a polymer chemistry perspective, it’s a challenge, but if an outer layer of polyethylene could be co-extruded with an inner layer of antimicrobial-infused pullulan, it would go a long way in making packaged meat products safer for consumers.